Geoscience Reference
In-Depth Information
FIG
141.
Hastings Castle, foreshore and cliff (Fig. 140,
a1
). (Copyright Sylvia Cordaiy
Photo Library Ltd)
The layering of the Hastings Beds in this Landscape is generally near to horizont-
al, and consists of alternations of sandstones and mudstones on many scales. The sand-
stones were mainly deposited in Early Cretaceous river channels and at river mouths,
while the mudstones were formed in lakes or on river floodplains. Two groups of sand-
stone layers are particularly important: an early, lower group called the Ashdown Sand
and a later, upper group called the Tunbridge Wells Sand. They are separated by a mud-
rich interval known as the Wadhurst Clay (Fig. 139). These changes of rock type have
locally influenced the slopes that have formed during the erosion of much of the to-
pography. At Hastings (
a1
), the castle was constructed on a prominent sandstone layer
within the Wadhurst interval, which has been eroded by coastal storms to produce a
distinctive cliff feature (Fig. 141).
The bedrock was cut by faults that became active during the movement of the
crust in mid-Tertiary times, when the Weald uplift was forming. Displacements along
these faults have disrupted the regular layer pattern of the bedrock, which has, in turn,
caused variation in local slope erosion. The commonest fault direction is WNW-ESE,
and some of the main valleys, such as those of the Rother and Brede, locally trend par-
allel to particular faults (Fig. 149, page 192).
Landscape B: The Low Weald
The Low Weald is defined by the presence of the Early Cretaceous Weald Clay just
below any surface blanket that happens to be present locally. It forms a wide and rather
featureless belt of scenery along the northern margin of Area 7.
To the east of this Landscape, the Weald Clay bedrock forms an irregular but
generally linear slope feature that was eroded in the Bilsington area (
b1
) before the
coastal-zone deposition of Dungeness and Romney Marsh began. The irregularities of
